1. Field
This invention relates generally to the field of weight change responsive steering mechanisms, such as those commonly used with skateboards, and more specifically to a novel, simplified steering mechanism which offers the advantages of simultaneous steering and wheel tilting.
2. Prior Art
Steering mechanisms which respond to weight changes made by the operator/rider, usually known as trucks, are well known in the art. In most instances, trucks are attached to the bottom broad face of a platform, or similar planar member, upon which a weight rests or stands. Responsive to a change in the center of mass of the weight from one side to another, the platform tilts slightly to cause the truck to change the direction in which the corresponding wheels are pointing. Thus, a rider balanced atop a skateboard shifts his or her weight to one side or the other depending on the direction desired.
Generally, the wheels used with such trucks are relatively small in diameter, while having a relatively substantial width (the width often exceeds the diameter). Also, these wheels are usually close together, and therefore disposed underneath the platform. U.S. Pat. Nos. 2,509,324, issued to Van Horn in 1950, and U.S. Pat. No. 4,398,734, issued to Barnard in 1983, are typical of such trucks and wheels, and embody the typical arrangement in skateboards.
Both the Barnard and Van Horn patents disclose a plunger which is rigidly affixed at one end to the bottom face of a platform, the free end of the plunger extending downwardly therefrom. An axle having wheels rotatably attached at both ends is affixed to the free end of the plunger, the axle including a leg which extends forwardly. The forwardly extending end of the leg is in communication with a leg holder such that universal movement of the leg's free end is allowed.
In this manner, when the center of mass of a weight atop the platform is shifted to one side of the platform or the other, the platform and plunger correspondingly shift or tilt slightly, the plunger thereby causing the axle and wheels to turn in a different direction.
While adequate for a number of applications, the type of steering truck just described includes a number of disadvantages as well. For example, this configuration requires that the wheels be fairly close together. This can become a problem when the truck is called upon to make sharp turns since the platform may tilt far enough over to make contact with the wheels. Thus, this configuration not only limits the turning radius of this type of steering mechanism, but the platform contacting the wheels can cause a dangerous situation as well.
For instance, many skateboard riders lean extremely hard into sharp turns, particularly when traveling at a high rate of speed. When this happens, it is not only conceivable, but probable, that the exertion of such a force on the edge of the skateboard platform will cause a tilting of the platform with respect to the wheels such that the platform and wheels come in contact, thereby throwing the rider off balance and probably causing an accident. Also, if the platform can come into contact with the wheels during such a turn, undue wear and tear is caused on both the wheels and the platform.
Another problem caused by the configuration mentioned above is the size of the wheels. While providing a greater contact area with the ground, such wheels cannot tilt into a turn to assist in gripping the ground surface. Indeed, even assuming that such steering mechanisms provide for tilt in the wheels, which they do not, the extra wide wheels commonly used on skateboards could not be tilted during a turning maneuver without virtually eliminating the ground contact sought to be maintained by use of the wide wheels. Thus, without the ability to tilt, horizontal forces experienced during the course of a turn, caused by the tendency of an object to travel in straight path, must be completely absorbed by frictional forces between the wheels and the ground.
Furthermore, Applicant's prior applications dealing with steering mechanisms which have both steering and tilting capabilities are fairly complex. Hence, the steering mechanisms covered by these applications can be more expensive than desired, and may tend to break down and be more difficult to repair and maintain.
Therefore, there exists in the prior art a legitimate need for a steering mechanism which not only provides steering capabilities, but also provides tilting capabilities as well to allow enhanced turning capacity. Further, a steering mechanism which provides these capabilities and which is constructed in a simpler fashion is even more desirable.